Needle breakage safety device

ABSTRACT

A needle breakage safety device for knitting machines. The shock wave produced by a needle break is propagated through the needle bed to a freely displaceable, electrically conductive sphere or ball. The movement of the ball closes an electrical circuit which disengages the needle carriage drive to prevent further damage. The ball may be placed in a slightly inclined trough affixed to the needle bed, or it may be mounted on a flexible spring arm in the manner of a bell clapper.

United States Patent [191 Graser [451- Oct, 1, 1974 NEEDLE BREAKAGE SAFETY DEVICE [75] Inventor: Anton Graser,

Westhausen-Reichenbach, Germany [73] Assignee: Universal Maschinenfabrik Dr.

Rudolf Schieber KG, Westhausen, Germany '22 Filed: Nov. 10,1972

21 Appl.No.:305,393

[30] Foreign Application Priority Data Primary ExaminerRonald Feldbaum Attorney, Agent, or FirmSughrue, Rothwell, Mion, Zinn & Macpeak 57 ABSTRACT A needle breakage safety device for knitting machines. The shock wave produced by a needle break is propagated through theneedle bed to a freely displaceable, electrically conductive sphere or ball. The movement of the ball closes an electrical circuit which disengages the needle carriage drive to prevent further damage. The ball may be placed in a slightly inclined trough affixed to the needle bed, or it may be mounted on a flexible spring arm in the manner of a bell clapper.

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NEEDLE BREAKAGE SAFETY DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to devices for safeguarding against damage resulting from needle breakage on knitting machines.

2. Prior Art Straight and circular knitting machines are generally provided with safety devices which either switch off the machine after a needle break or prevent a further runthrough of the sliding carriage in order to avoid any further breakage of needle feet and damage to the needle beds as a result of the damage which occurred when the first needle broke.

Safety devices of this type operating on the principle of an impact safety mechanism have previously been used on straight and circular knitting machines. In an impact safety device overload levers are mounted on 7 the sliding carriage entrainment of the drive means. The shock produced by breakage of a needle causes these levers to tilt sideways and to activate an electrical disengaging device.

In the case of knitting machines having additional selecting instruments for the needles, for example several rows of Jacquard rods, the force needed to pull the sliding carriage over the needles and rods is considerable. Furthermore, the sliding carriage of a knitting machine of this type is heavier than that of a lesscomplicated machine. The entrainment force and the inert mass of the moving sliding carriage are so great that it is not possible to release the disengaging device by way of the above-mentioned impact safety mechanism as a result, for example, of the relatively small shock caused by the breakage of only one needle.

For this reason, a needle breakage safety device has been developed which picks up the impact wave occurring on needle breakage via a sound microphone and activates a disengaging device for the sliding carriage of the knitting machines by way of electronic amplifying means. The advantage of this type of safety device is that it can be used both with straight and circular knitting machines. However, this type of device is extremely expensive to produce.

SUMMARY OF THE INVENTION The object of the present invention is thus to obviate the disadvantages of known needle breakage safety devices and to create a simple and reliable needle breakage safety device for knitting machines.

This problem is solved according to the invention by a needle breakage safety device operating on the principle of the impact safety mechanism in that a movable member abuts against each of the front faces of the needle beds, said member being repelled by the impact wave produced by the needle breakage. An electrical contact is provided which is activated by the repelled member and which controls the disengaging device of the knitting machine.

The device according to the invention is simple in construction and has the advantage that only the impact waves occurring in the needle bed initiate the switching process.

According to one embodiment of the invention the member is mounted on a free swinging spring and swings against a flexible contact.

According to another embodiment of the invention the member consists of a sphere which is disposed on an inclined track serving as the electrical contact and which abuts against a flexible contact.

In the case of a highly refined knitting machine the device is advantageously so constructed that the inclined position of the track is infinitely adjustable. In this way the device can be adjusted in respect of the various refinements to the machine or of the varying weights of the sliding carriage.

With a highly refined knitting machine the bar of the needle bed easily springs to the side in the case of individual upright needles so that the impact wave is smaller and the path of the sphere shorter. However, it is sufficient to open the contact. The needle breakage safety device according to'the invention may also be constructed with the sphere disposed between two tracks inclined in opposite directions.

In another embodiment the member closes the contact in its rest position and opens it when it swings or rolls away whereupon an associated relay activates the disengaging device.

In a refinement of the needle breakage device according to the invention a switching device is provided for the synchronized interruption of the contact between the contact points or between the relay and the disengaging device each time the sliding carriage leaves the region of the needles. In this way the disengaging device is prevented from being released and the knitting machine from being switched .off as a result of the switching or racking mechanisms on straight knitting machines.

BRIEF DESCRIPTION OF THE DRAWINGS Various embodiments of the invention are described in the drawings which will be described in more detail hereafter. In the drawings:

FIG. I shows a front view of a-straight knitting machine,

FIG. 2 shows a side view of the needle bed support with the needle beds having a sliding carriage and a sphere switching device mounted thereon,

FIG. 3 shows a plan view of a spherical switching device,

FIG. 4 shows a section of a spherical switching device along the line IVIV in FIG. 3,

FIG. 5 shows a plan view of a spherical switching device with an adjustable track slope,

FIG. 6 shows a sectional view along the line VIVI in FIG. 5,

FIG. 7 shows an electromagnetic device for releasing the disengaging device in the blocked state,

FIG. 8 shows the device of FIG. 7 in the released state,

FIG. 9 shows a plan view of a spherical switching device having tracks inclined in opposite directions,

FIG. 10 shows a section along the line X-X in FIG. 9,

FIG. 11 shows a switching device having a member which is mounted on a free swinging spring, and

FIG. 12 shows a switching device wherein a normally closed electrical circuit is opened by a'needle break shock.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a front view of a straight knitting machine on which the needle breakage safety device according to the invention can be mounted. The sliding carriage 13 is connected to an endless chain 14. The chain is driven by a chain wheel 15, which is connected via coupling means (not shown) to a drive mechanism (not shown).

FIG. 2 shows a diagrammatic side view of the needle beds 3 and 4 with the sliding carriage disposed thereon. The needle bed support 1 is attached to the machine frame 16. A spherical switching device 2 is mounted on each of the needle beds 3 and 4. When an impact wave occurs the spherical switching devices effect a rolling movement. These impact waves occur when needle or rod feet break during the passage of the needles and rods through the lock in the sliding carriage 13. The im pact waves bring about a switching process by way of the spheres and thus release the disengaging device for the sliding carriage drive. In this way further damage to needles and needle beds by another passage of the sliding carriage after the first needle break, is avoided.

A switching device is provided for the synchronized interruption of the connection between the spherical switching devices and the disengaging device each time the sliding carriage leaves the region of the needles in order to prevent the disengaging device from being released by the spherical switching devices as a result of impact waves produced, for example, by the switching of the racking mechanism on a knitting machine. In .FIG. 1 the regions beyond the needles are designated by x. When the sliding carriage 13 passes a timing or synchronization point 17 outside the region of the needles, a connection between the monitoring device having the spherical switching devices to pick up the impact waves and the disengaging device for the sliding carriage, is interrupted. When the sliding carriage enters the region containing the needles the interrupted connection is again restored. In this way the shocks or movements of the needle beds arising during switching of a racking mechanism, for example, do not release the disengaging device unnecessarily when the sliding carriage 13 is outside the region of the needles.

FIG. 3 shows the end of a needle bed 3 having a spherical switching device 2 mounted thereon. The sphere is in a rest position and abuts against the needle bed 3.

FIG. 4 shows a sectional view along the line IVIV of FIG. 3. When a needle or rod breakage produces a shock wave in the needle bed the sphere 5 rolls in the direction of the arrow and touches the contact plate 6 which closes a circuit and activates the disengaging device. To prevent the jumping out of the sphere when a particularly powerful impact wave occurs, the contact plate 6 is constructed to partially overlie the sphere 5.

The strength of the impact waves produced in the needle beds by the breakage of needle or rod feet depends on the sensitivity of the machine and the weight of the sliding carriage. Larger impact waves occur with coarse graduations and heavy sliding carriages than with fine graduations and light sliding carriages. To allow for these variations the spherical switching device according to FIGS. 5 and 6 may be so constructed that the inclination of the contact surface 9 of the sphere 5 is infinitely adjustable by means of a microscrew 10.

FIG. 7 represents the part of the disengaging device activated by the spherical switching device in the blocked state. The electromagnet 11 is mounted on the machine frame 16. It attracts one end of a pivotally mounted, two-armed lever 12. The other end of this lever 12 holds a lever 18 against the tension ofits spring as long as the electromagnet 11 is not energized. When the lever 18 is in the position indicated, a switching bar 19 is positioned so that a coupling (not shown) connected to the chain wheel 15. is engaged.

When an impact wave is produced the circuit is closed or interrupted by the movement of a sphere 5 and the electromagnet is supplied with power as long as the sliding carriage 13 is in the region of the needles. As a result, the lever 12 is raised and the lever 18 is released. As a result of its spring tensioning the lever 18 moves the switching bar 19 in the direction of the arrow in FIG. 8. The coupling (not shown) is released by the movement of the switching bar 19 and the sliding carriage 13 is brought to a standstill. FIG. 8 shows the device in the released position.

FIGS. 9 and 10 show a switching device which can respond to impact waves in both directions. In this embodiment the sphere 5 is located at the intersection of two tracks or roller paths 20 and 21, which are inclined in opposite directions.

FIG. 11 shows the needle bed 3 with a sphere 5 abutting against it. This sphere 5 is mounted in a free swinging manner on the flat spring 23. The mounting support 24 of the flat spring 23 is fixed to the needle bed support 1. When impact waves are produced in the needle bed the sphere wings away from the needle bed and touches the flexible contact plate 6, thus closing the circuit to the disengaging device. This plate 6 may be adjusted in the mounting support 26 by means of a rotatable screw 25.

FIG. 12 shows a device which switches off the machine when a circuit is interrupted. If an impact wave arises in the needle bed the sphere 5 loses its contact with the needle bed for a short period of time. The circuit is interrupted momentarily and as a result the disengaging device is activated, for example by a relay whose spring loaded plunger closes contacts to energize the electromagnet 1 1 when the circuit to the relay coil is interrupted by movement of the sphere 5.

What is claimed is:

1. In a needle breakage safety device for knitting machines including at least one needle bed and means responsive to a needle break for producing an electrical control signal, the improvement characterized by said means comprising a movable member, support means for said movable member for normally maintaining said movable member in contact with said needle bed, an electrical contact disposed closely adjacent to but spaced from said needle bed whereby a shock wave produced by a needle break will be propagated through said needle bed causing said movable member to move relative to said needle bed in engagement with said electrical contact to produce said control signal and means for adjusting the spacing between said electrical contact and said movable member; said support means being comprised of a spring member fixedly secured at one end to said needle bed and carrying said movable member at the opposite end thereof for normally maintaining said movable member in contact with said needle bed.

2. In a needle breakage safety device as set forth in claim 1 wherein said electrical contact is comprised of a flexible resilient member. 

1. In a needle breakage safety device for knitting machines including at least one needle bed and means responsive to a needle break for producing an electrical control signal, the improvement characterized by said means comprising a movable member, support means for said movable member for normally maintaining said movable member in contact with said needle bed, an electrical contact disposed closely adjacent to but spaced from said needle bed whereby a shock wave produced by a needle break will be propagated through said needle bed causing said movable member to move relative to said needle bed in engagement with said electrical contact to produce said control signal and means for adjusting the spacing between said electrical contact and said movable member; said support means being comprised of a spring member fixedly secured at one end to said needle bed and carrying said movable member at the opposite end thereof for normally maintaining said movable member in contact with said needle bed.
 2. In a needle breakage safety device as set forth in claim 1 wherein said electrical contact is comprised of a flexible resilient member. 